/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.lucene.xmlparser.webdemo;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.Enumeration;
import java.util.Properties;
import java.util.StringTokenizer;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.standard.StandardAnalyzer;
import org.apache.lucene.document.Document;
import org.apache.lucene.document.Field;
import org.apache.lucene.index.CorruptIndexException;
import org.apache.lucene.index.IndexWriter;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.ScoreDoc;
import org.apache.lucene.search.TopDocs;
import org.apache.lucene.store.RAMDirectory;
import org.apache.lucene.xmlparser.CorePlusExtensionsParser;
import org.apache.lucene.xmlparser.QueryTemplateManager;

public class FormBasedXmlQueryDemo extends HttpServlet {

	/**
	 * 版本序列化ID
	 */
	private static final long serialVersionUID = -8213647293726912161L;
	private QueryTemplateManager queryTemplateManager;
	private CorePlusExtensionsParser xmlParser;
	private IndexSearcher searcher;
	private Analyzer analyzer = new StandardAnalyzer(org.apache.lucene.util.Version.LUCENE_CURRENT);

	/* (non-Javadoc)
	 * @see javax.servlet.GenericServlet#init(javax.servlet.ServletConfig)
	 */
	@Override
	public void init(ServletConfig config) throws ServletException {
		super.init(config);
		try {
			openExampleIndex();

			// load servlet configuration settings
			String xslFile = config.getInitParameter("xslFile");
			String defaultStandardQueryParserField = config
					.getInitParameter("defaultStandardQueryParserField");

			// Load and cache choice of XSL query template using
			// QueryTemplateManager
			queryTemplateManager = new QueryTemplateManager(getServletContext()
					.getResourceAsStream("/WEB-INF/" + xslFile));

			// initialize an XML Query Parser for use by all threads
			xmlParser = new CorePlusExtensionsParser(
					defaultStandardQueryParserField, analyzer);
		} catch (Exception e) {
			throw new ServletException("Error loading query template", e);
		}
	}

	@Override
	protected void doPost(HttpServletRequest request,
			HttpServletResponse response) throws ServletException, IOException {
		// Take all completed form fields and add to a Properties object
		Properties completedFormFields = new Properties();
		Enumeration pNames = request.getParameterNames();
		while (pNames.hasMoreElements()) {
			String propName = (String) pNames.nextElement();
			String value = request.getParameter(propName);
			if ((value != null) && (value.trim().length() > 0)) {
				completedFormFields.setProperty(propName, value);
			}
		}

		try {

			// Create an XML query by populating template with given user
			// criteria
			org.w3c.dom.Document xmlQuery = queryTemplateManager
					.getQueryAsDOM(completedFormFields);

			// Parse the XML to produce a Lucene query
			Query query = xmlParser.getQuery(xmlQuery.getDocumentElement());

			// Run the query
			TopDocs topDocs = searcher.search(query, 10);

			// and package the results and forward to JSP
			if (topDocs != null) {
				ScoreDoc[] sd = topDocs.scoreDocs;
				Document[] results = new Document[sd.length];
				for (int i = 0; i < results.length; i++) {
					results[i] = searcher.doc(sd[i].doc);
					request.setAttribute("results", results);
				}
			}
			RequestDispatcher dispatcher = getServletContext()
					.getRequestDispatcher("/index2.jsp");
			dispatcher.forward(request, response);
		} catch (Exception e) {
			throw new ServletException("Error processing query", e);
		}
	}

	private void openExampleIndex() throws CorruptIndexException, IOException {

		// Create a RAM-based index from our test data file
		RAMDirectory rd = new RAMDirectory();
		IndexWriter writer = new IndexWriter(rd, analyzer, IndexWriter.MaxFieldLength.LIMITED);
		InputStream dataIn = getServletContext().getResourceAsStream("/WEB-INF/data.tsv");
		BufferedReader br = new BufferedReader(new InputStreamReader(dataIn));
		String line = br.readLine();
		while (line != null) {
			line = line.trim();
			if (line.length() > 0) {
				// parse row and create a document
				StringTokenizer st = new StringTokenizer(line, "\t");
				Document doc = new Document();
				doc.add(new Field("location", st.nextToken(), Field.Store.YES,
						Field.Index.ANALYZED_NO_NORMS));
				doc.add(new Field("salary", st.nextToken(), Field.Store.YES,
						Field.Index.ANALYZED_NO_NORMS));
				doc.add(new Field("type", st.nextToken(), Field.Store.YES,
						Field.Index.ANALYZED_NO_NORMS));
				doc.add(new Field("description", st.nextToken(),
						Field.Store.YES, Field.Index.ANALYZED));
				writer.addDocument(doc);
			}
			line = br.readLine();
		}
		writer.close();

		// open searcher
		searcher = new IndexSearcher(rd, true);
	}
}
